Stomp kicks in mma

why haven't I ever seen anyone use an earth front kick (stomping with the arch of the foot) on a standing opponent (like in the shin or toes in the clench)? I understand why you can't do it to grounded opponents. it seems just as risky as kneeing someone. Is it against the rules? Sorry for the awkward wording.

You can stomp on the toes in many MMA organizations (including the UFC) and you can side-kick the knee, which is kind of like a stomp at that angle. Most people don't do it because the stomps to the feet don't really do much when the floor is somewhat cushioned and kicks to the knee are often considered "dirty" because you could seriously end someone's MMA career that way. They do show up from time to time, though--I know that Jon Jones side-kicked Shogun in the knees in their fight and I believe Clay Guida uses foot stomps fairly regularly in the clinch against the cage.

If you watch the old Pride fights, you will see stomp kicks to a downed opponent quite regularly. Those are not allowed in the UFC styles rules.

The first person in the UFC (I believe) to use the foot stomp was Marco Ruas, who also was the first to use the Thai kick to great success. You will see the foot stomp with fighters that have a good ground game or takedown defense because they arent' afraid of going to the ground when they do it. Most dont' do it, but that doesn't mean it's not effective they just don't train it (anyone remember never seeing hammerfists in MMA until Sakuraba started using them?) Also, many don't use the heel portion of their foot to the small bones and those that do, you will see a good reaction of the person getting stomped moving their feet around like they are on hot rocks and focusing on getting out of that position.

It's kind of like those punches to the ribs while on the ground. To a trained guy it's not a fight ender by any means, but over time they build until you can't ignore them anymore.